Accumulation of platelets as a key mechanism of human erection.

In this study, the role of platelets in the human erectile response was assessed. Twenty patients with erectile dysfunction were studied by means of (111)In-oxine-platelets and blood pool imaging using 99mTc. Seventeen patients received intracavernously prostaglandin E1, and three patients received papaverine together with phentolamine. In patients who responded with erection, an increase by between 16 to 137% platelets/ml and a rapid platelet accumulation in the penis during the initial phase of erection were observed. In patients without erection, no change in local platelet concentration occurred. It is likely that platelets play a major role in human erection, probably by temporary activation, thereby regulating venous outflow.